New materials, methods cut bridge construction cost

Pennsylvania Department of Transportation bridge engineer Bill Koller shows plastic material that wraps layers of gravel in a new method of building bridge abutments, near Lincolnville in Crawford County July 26. VALERIE MYERSERIE TIMES-NEWS

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CANADOHTA LAKE -- A bridge under construction in northern Crawford County is supported by walls made of compacted stone and permeable fabric.

The Brown Hill Road bridge in Bloomfield Township is the first state-owned bridge in the region to be built with the layered gravel and fabric. The walls are stronger and less expensive than traditional concrete bridge abutments and take less time to install, which helps to keep costs down, said Bill Koller, Pennsylvania Department of Transportation's district bridge engineer.

"It takes a lot less time, and doesn't take a lot of people," Koller said of the new process.

Crews accustomed to working with the materials can build a bridge support in one day, compared to the 10 days to two weeks it takes to form, pour and cure a concrete abutment, Koller said.

It's not known how much PennDOT will save by using the new technology on the Brown Hill Road bridge, but in neighboring Ohio and New York, where geosynthetic reinforced-soil walls, as they're called, have been used in bridge supports for several years, "the savings are at least one-third to one-half," Koller said.

Additionally, the new bridge supports can be built on top of existing concrete abutments, saving the time and cost of breaking them up and removing them.

At the Brown Hill Road bridge, new support walls built on top of the old concrete abutment are also environmentally friendly.

"We don't have to work in the stream below the bridge at all, as we would to build a concrete abutment," Koller said. "That helps us out a lot and reduces the impacts on the stream," called Federal Run.

The new technology also will benefit drivers, PennDOT spokesman Jim Carroll said.

"Construction will be finished sooner. Drivers will appreciate less detour time," Carroll said.

Concrete beams precast by PennDOT employees during down time last winter also are being used in the Brown Hill Road project. PennDOT expects those and other precast components to save the department $700,000 this year, Carroll said.